The resolution of a single image captured or acquired by an image capture device, such as a film or digital camera, is finite and therefore limited. Generally the resolution of an electronic imaging device is a tradeoff between the number of picture elements (pixels) and cost. Prior known devices scan an object, by acquiring a plurality of subimages of the object, to generate a high resolution image.
One known type of electronic imaging device, known as a document scanner, is suitable for acquiring images of flat, two dimensional objects of a limited size. In a document scanner, the object and the image detector are positioned a very small, fixed distance relative to each other, and the object or the image detector moves. Examples of document scanners are flatbed scanners, sheet fed scanners, handheld scanners, fax machines and copiers. Each of these scanners is limited to scanning two dimensional objects such as sheets of paper. Handheld scanners are difficult to use. Flatbed and sheet fed scanners can only scan up to a selected maximum size, generally the size of legal or letter size paper.
Other scanners, sometimes known as “over the desk” scanners, are spaced relative to the object, and can acquire images of three dimensional objects and images of larger objects than most document scanners. Although some scanners of this type move the image detector or the object, preferably the image detector and object remain stationary during image acquisition. U.S. Pat. No. 5,686,960 to Sussman et al. discloses a scanner having a stationary image detector spaced above the object and a rotating disk with a preselected number of deflectors that deflect tiles or sub-images of the object through a lens onto the image detector. Sussman et al. also discloses a scanner having a stationary image detector spaced above the object and a pair of selectively rotatable mirrors that reflect tiles or sub-images of the object through a lens onto the image detector. The image path from the object to the reflector or mirror in Sussman et al. is oblique rather than perpendicular to the object for all but at most one tile or subimage.
Generally for “over the desk” scanners with a stationary object and image detector, the image path from the object to the image detector is oblique or slanted. Such an oblique image path can distort and defocus the subimage acquired. U.S. Pat. No. 6,512,539 to Dance et al. discloses a scanner having a stationary image detector spaced above the object and an inner rotating mirror that receives light from four outer mirrors. Each outer mirror is centered over a quadrant of the object so that the image paths are perpendicular to the object. The scanner disclosed by Dance et al. requires an outer mirror for each subimage.
Prior known security or surveillance systems generally have stationary cameras or motor driven cameras that tilt, pan and zoom. Stationary cameras have a limited field of view and generally have limited resolution. Motor driven cameras generally sweep the area of interest over a period of multiple seconds, such that portions of the area of interest are missed by the camera for multiple seconds.
Some prior known systems for taking panoramic pictures use convex mirror systems with a camera to acquire the entire panorama in a single shot. These systems provide relatively low resolution pictures. Other systems for taking panoramic pictures rotate the camera about a center point.